Excellent know-how of ISDN Call processing, like Base Call and Supplementary Services
Excellent know-how of ETSI or ITU-T standards in this area (e.g. Q.931, )
Excellent know-how in ASN.1 (Supplementary Services like CCBS/CCNR etc.)
Excellent know-how in all kind of telephony features like Inquiry, Call Waiting, Intrusion, Call Completion, Conference Call, Transfer Call etc.
Excellent know-how of general telephony interfaces/services (e.g. ISDN BRA/PRA, Analogue, QSIG, plus proprietary interfaces)
Know-how in implementing/designing telephony services like Conference Services, Voicemail-Services, Call recorders etc.